1. Field of the Invention
The present invention relates to a motorcycle, and more particularly to a motorcycle in which an exhaust pipe (a catalyst apparatus) is arranged below an engine mounted on a vehicle body of the motorcycle, and at least an under side of the vehicle body is covered by a cowling.
2. Description of the Related Art
In recent years, in the field of motorcycles, it has been desired to remove hydro carbons (HC), nitrogen oxides (NOx) and the like contained in exhaust gas. Japanese Unexamined Patent Publication No. 6-26375 discloses a technique in which an exhaust pipe of a motorcycle is provided with a catalyst apparatus for purifying exhaust gas. The exhaust pipe is extended to a rear side from a front side through a lower side, of an engine of the motorcycle, and the catalyst apparatus is arranged at the lower side of the engine. Further, a vehicle body of the motorcycle is covered by a cowling.
Since the cowling is formed by synthetic resin in most cases, and the exhaust pipe, particularly the catalyst apparatus, reaches a high temperature, the cowling can be exposed to a thermal effect such as deformation, discoloration or the like if the cowling exists near the catalyst apparatus. Further, since the catalyst apparatus normally has a larger diameter than the exhaust pipe, a minimum road clearance of the motorcycle is reduced and a bank angle of the motorcycle becomes lower if a lower side of the catalyst apparatus is covered by the cowling. Accordingly, as shown in FIG. 7, a cowling 101 is set apart from a catalyst apparatus 100 and an exhaust pipe 104 by forming a notch-shaped opening 102 in a lower surface of the cowling 101, thereby making a road clearance of the cowling 101 larger and making a bank angle larger.
However, if the notch-shaped opening 102 is formed as mentioned above, a strength of both end portions 102A, 102A of the notch-shaped opening 102 is lowered, and both end portions 102A, 102A are subject to flip-flop and generation of vibrations while the motorcycle is moving. In order to compensate for the strength of the end portions 102A, 102A, a reinforcing member 103 can be provided in such a manner as to bridge the two end portions 102A, 102A. However, since the reinforcing member 103 is disposed close to the exhaust pipe 104 and the catalyst apparatus 100, and the heat of the exhaust pipe 104 and the catalyst apparatus 100 is transmitted to the cowling via the reinforcing member 103, this structure is not preferable. Further, since the vehicle body is lowered somewhat by the presence of the reinforcing member 103, the minimum road clearance becomes smaller.